MADRID (AP) — American veteran Christopher Horner completed the biggest victory of his career on Sunday, winning the Spanish Vuelta at 41 to become the oldest champion of one of cycling's three-week grand tours.

Horner successfully navigated the final flat stage to arrive in Madrid with his RadioShack-Leopard teammates after effectively clinching the race in the mountains over the last three days.

Vincenzo Nibali of Italy and Alejandro Valverde of Spain — both former winners— were second and third, respectively.

"This is a very spectacular moment," Horner said. "Many thanks to my competitors. Nibali was spectacular, Valverde also. It's a very special moment to be here with these great cyclists on my left and right."

The previous oldest winner for one of the three grand tours— the Vuelta, Tour de France and Giro d'Italia— was Fermin Lambot, who won the 1922 Tour at 36.

Horner, who will turn 42 next month, beat nearest challenger Nibali by finishing ahead of the Italian in each of the final three mountainous stages before Sunday's 68-mile ride from Leganes to Madrid.

Michael Matthews of Australia won the 21st and final stage in a sprint.

"We only had four other teammates to help with the sprint today, but everyone did their job 100 percent to help me get the win," Matthews said after the second stage win at this Vuelta for Orica Greenedge.

This edition of the Vuelta, the 68th, had been crafted to favor strong climbers with 13 of its 21 stages set in the mountains.

And Horner made the most of it, consistently pulling away with his high riding stance and a wry smile on his face while younger rivals agonized behind him.

The veteran rider was not among the favorites entering the race, but he joined them upon winning the third stage. That made him the oldest rider to ever win a stage at a grand tour, breaking the former record held by Pino Cerami, who won a Tour stage at 41 years, 2 months.

In the decisive stage Saturday, Horner resisted Nibali's repeated attacks before leaving him behind in the fog as he surged up the Alto de L'Angliru peak, increasing his lead from 3 to 37 seconds.

Horner turned professional in 1995. His previous wins included the Tour of Georgia in 2003, the Tour of the Basque Country, a northern region on Spain, in 2010, and the Tour of California in 2011.

Euskaltel-Euskadi, the financially troubled Basque team that Forumula One driver Fernando Alonso is considering sponsoring, finished as the best team at the race. The rest of the peloton let Euskaltel-Euskadi ride in front as it entered the city center.